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Yadav HOS, Chakravarty C. Thiolated gold nanoparticle solvation in near-critical fluids: The role of density, temperature, and topology. J Chem Phys 2017; 146:174902. [DOI: 10.1063/1.4982755] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Hari O. S. Yadav
- Department of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India
| | - Charusita Chakravarty
- Department of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India
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2
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Yu N, Ghosh A, Hagan MF. Faceted particles formed by the frustrated packing of anisotropic colloids on curved surfaces. SOFT MATTER 2016; 12:8990-8998. [PMID: 27748486 PMCID: PMC5287255 DOI: 10.1039/c6sm01498d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We use computer simulations and simple theoretical models to analyze the morphologies that result when rod-like particles end-attach onto a curved surface, creating a finite-thickness monolayer aligned with the surface normal. This geometry leads to two forms of frustration, one associated with the incompatibility of hexagonal order on surfaces with Gaussian curvature, and the second reflecting the deformation of a layer with finite thickness on a surface with non-zero mean curvature. We show that the latter effect leads to a faceting mechanism. Above threshold values of inter-particle attraction strength and surface mean curvature, the adsorbed layer undergoes a transition from orientational disorder to an ordered state that is demarcated by reproducible patterns of line defects. The number of facets is controlled by the competition between line defect energy and intra-facet strain. Tuning control parameters thus leads to a rich variety of morphologies, including icosahedral particles and irregular polyhedra. In addition to suggesting a new strategy for the synthesis of aspherical particles with tunable symmetries, our results may shed light on recent experiments in which rod-like HIV GAG proteins assemble around nanoscale particles.
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Affiliation(s)
- Naiyin Yu
- Martin Fisher School of Physics, Brandeis University, Waltham, MA, USA
| | - Abhijit Ghosh
- Martin Fisher School of Physics, Brandeis University, Waltham, MA, USA
| | - Michael F Hagan
- Martin Fisher School of Physics, Brandeis University, Waltham, MA, USA
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3
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Widmer-Cooper A, Geissler PL. Ligand-Mediated Interactions between Nanoscale Surfaces Depend Sensitively and Nonlinearly on Temperature, Facet Dimensions, and Ligand Coverage. ACS NANO 2016; 10:1877-87. [PMID: 26756464 DOI: 10.1021/acsnano.5b05569] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Nanoparticles are often covered in ligand monolayers, which can undergo a temperature-dependent order-disorder transition that switches the particle-particle interaction from repulsive to attractive in solution. In this work, we examine how changes in the ligand surface coverage and facet dimensions affect the ordering of ligands, the arrangement of nearby solvent molecules, and the interaction between ligand monolayers on different particles. In particular, we consider the case of strongly bound octadecyl ligands on the (100) facet of CdS in the presence of an explicit n-hexane solvent. Depending on the facet dimensions and surface coverage, we observe three distinct ordered states that differ in how the ligands are packed together, and which affect the thickness of the ligand shell and the structure of the ligand-solvent interface. The temperature dependence of the order-disorder transition also broadens and shifts to lower temperature in a nonlinear manner as the nanoscale is approached from above. We find that ligands on nanoscale facets can behave very similarly to those on macroscopic surfaces in solution, and that some facet dimensions affect the ligand alignment more strongly than others. As the ligands order, the interaction between opposing monolayers becomes attractive, even well below full surface coverage. The strength of attraction per unit surface area is strongly affected by ligand coverage, but only weakly by facet width. Conversely, we find that bringing two monolayers together just above the order-disorder transition temperature can induce ordering and attraction.
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Affiliation(s)
- Asaph Widmer-Cooper
- School of Chemistry, University of Sydney , Sydney, New South Wales 2006, Australia
| | - Phillip L Geissler
- Department of Chemistry, University of California Berkeley , Berkeley, California 94720, United States
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4
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Zhang H, Li F, Xiao Q, Lin H. Conformation of Capping Ligands on Nanoplates: Facet-Edge-Induced Disorder and Self-Assembly-Related Ordering Revealed by Sum Frequency Generation Spectroscopy. J Phys Chem Lett 2015; 6:2170-6. [PMID: 26266587 DOI: 10.1021/acs.jpclett.5b00717] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Surface-curvature-amplified conformational disorder in alkyl capping ligands has been observed previously when the nanoparticle radii approach the ligand length. Herein, sum frequency generation studies on oleic-acid-capped nanoplates show that even on faceted surfaces with dimensions tens of times greater than the ligand length a significant proportion of gauche defects exist in the capping layer. The molecular disorder on the nanosized facets is attributed to a facet-edge effect, which is diminished when increasing the facet size or assembling the nanofacets side to side. This feature is further explored to probe the self-assembly dynamics of nanoplates.
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Affiliation(s)
- Hao Zhang
- †i-LAB, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, P. R. China
- ‡School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, P.R. China
| | - Fujin Li
- †i-LAB, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, P. R. China
| | - Qingbo Xiao
- †i-LAB, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, P. R. China
| | - Hongzhen Lin
- †i-LAB, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, P. R. China
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de Moura AF, Bernardino K, Dalmaschio CJ, Leite ER, Kotov NA. Thermodynamic insights into the self-assembly of capped nanoparticles using molecular dynamic simulations. Phys Chem Chem Phys 2015; 17:3820-31. [PMID: 25562068 DOI: 10.1039/c4cp03519d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Although the molecular modeling of self-assembling processes stands as a challenging research issue, there have been a number of breakthroughs in recent years. This report describes the use of large-scale molecular dynamics simulations with coarse grained models to study the spontaneous self-assembling of capped nanoparticles in chloroform suspension. A model system comprising 125 nanoparticles in chloroform evolved spontaneously from a regular array of independent nanoparticles to a single thread-like, ramified superstructure spanning the whole simulation box. The aggregation process proceeded by means of two complementary mechanisms, the first characterized by reactive collisions between monomers and oligomers, which were permanently trapped into the growing superstructure, and the second a slow structural reorganization of the nanoparticle packing. Altogether, these aggregation processes were over after ca. 0.6 μs and the system remained structurally and energetically stable until 1 μs. The thread-like structure closely resembles the TEM images of capped ZrO2, but a better comparison with experimental results was obtained by the deposition of the suspension over a graphene solid substrate, followed by the complete solvent evaporation. The agreement between the main structural features from this simulation and those from the TEM experiment was excellent and validated the model system. In order to shed further light on the origins of the stable aggregation of the nanoparticles, the Gibbs energy of aggregation was computed, along with its enthalpy and entropy contributions, both in chloroform and in a vacuum. The thermodynamic parameters arising from the modeling are consistent with larger nanoparticles in chloroform due to the solvent-swelled organic layer and the overall effect of the solvent was the partial destabilization of the aggregated state as compared to the vacuum system. The modeling strategy has been proved effective and reliable to describe the self-assembling of capped nanoparticles, but we must acknowledge the fact that larger model systems and longer timescales will be necessary in future investigations in order to assess structural and dynamical information approaching the behavior of macroscopic systems.
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Affiliation(s)
- André F de Moura
- Departamento de Química, Centro de Ciências Exatas e de Tecnologia, Universidade Federal de São Carlos, Rodovia Washington Luiz km 235, CP 676, CEP 13565-905, São Carlos, SP, Brasil.
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Bolintineanu DS, Lane JMD, Grest GS. Effects of functional groups and ionization on the structure of alkanethiol-coated gold nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:11075-11085. [PMID: 25162679 DOI: 10.1021/la502795z] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report classical atomistic molecular dynamics simulations of alkanethiol-coated gold nanoparticles solvated in water and decane, as well as at water/vapor interfaces. The structure of the coatings is analyzed as a function of various functional end groups, including amine and carboxyl groups in various ionization states. We study both neutral and charged end groups for two different chain lengths (9 and 17 carbons). For the charged end groups, we simulated both mono- and divalent counterions. For the longer alkanes, we find significant local bundling of chains on the nanoparticle surface, which results in highly asymmetric coatings. In general, the charged end groups attenuate this effect by enhancing the water solubility of the nanoparticles. On the basis of the coating structures and density profiles, we can qualitatively infer the overall solubility of the nanoparticles. This asymmetry in the alkanethiol coatings is likely to have a significant effect on aggregation behavior. Our simulations elucidate the mechanism by which modulating the end group charge state can be used to control coating structure and therefore nanoparticle solubility and aggregation behavior.
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Affiliation(s)
- Dan S Bolintineanu
- Sandia National Laboratories , Albuquerque, New Mexico 87185, United States
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Widmer-Cooper A, Geissler P. Orientational ordering of passivating ligands on CdS nanorods in solution generates strong rod-rod interactions. NANO LETTERS 2014; 14:57-65. [PMID: 24295449 DOI: 10.1021/nl403067p] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present the first nearly atomistic molecular dynamics study of nanorod-nanorod association in explicit solvent, showing that inter-rod forces can be dominated by microscopic factors absent in common continuum descriptions. Specifically, we find that alkane ligands on faceted CdS nanorods in n-hexane undergo a temperature-dependent order-disorder transition akin to that of self-assembled monolayers on macroscopic substrates. This collective ligand alignment organizes nearby solvent molecules, strongly influencing the statistics of rod-rod separation. The strong temperature dependence of this mechanism could be exploited in the laboratory to manipulate and optimize the assembly of ordered structures.
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Li Y, Yang Z, Hu N, Zhou R, Chen X. Insights into hydrogen bond dynamics at the interface of the charged monolayer-protected Au nanoparticle from molecular dynamics simulation. J Chem Phys 2013; 138:184703. [DOI: 10.1063/1.4803504] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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9
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Nayar D, Yadav HOS, Jabes BS, Chakravarty C. Relating Structure, Entropy, and Energy of Solvation of Nanoscale Solutes: Application to Gold Nanoparticle Dispersions. J Phys Chem B 2012; 116:13124-32. [DOI: 10.1021/jp307615f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Divya Nayar
- Department
of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India
| | | | - B. Shadrack Jabes
- Department
of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India
| | - Charusita Chakravarty
- Department
of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India
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10
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Sun L, Yang X, Wu B, Tang L. Molecular simulation of interaction between passivated gold nanoparticles in supercritical CO2. J Chem Phys 2011; 135:204703. [DOI: 10.1063/1.3661982] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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A molecular simulation of interactions between graphene nanosheets and supercritical CO2. J Colloid Interface Sci 2011; 361:1-8. [DOI: 10.1016/j.jcis.2011.05.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Revised: 05/06/2011] [Accepted: 05/08/2011] [Indexed: 11/20/2022]
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12
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Lal M, Plummer M, Purton J, Smith W. A computer simulation study of the interaction between passivated and bare gold nanoclusters. Proc Math Phys Eng Sci 2011. [DOI: 10.1098/rspa.2010.0513] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Molecular dynamics simulations have been performed with the objective of understanding the phenomenon of nanoparticle aggregation. We have attempted to calculate the free energy associated with the interaction between two 38-atom gold nanocores, with attached passivating thiol chains, in a supercritical ethane solvent and in the vacuum, and without passivating chains in ethane at the critical density and twice the critical density. Our model differs from those used by others in that each gold nanocore is bound by a realistic metal potential that is not formally rigid. In the case of the passivated nanoparticles, we observe profound structural changes in the nanocores, which radically affect the nature of the interaction between them—to the extent that fusion of the two gold nanocores cannot be prevented under the conditions examined. Bare nanocores, on the other hand, do not exhibit much structural change until close contact occurs. The fused nanocores in the passivated and bare nanocore systems have significantly different morphologies. There is evidence that at higher solvent density, the interaction between bare nanocores is slightly repulsive.
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Affiliation(s)
- Moti Lal
- Centre for Nanoscale Science, The Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, UK
| | - Martin Plummer
- Computational Science and Engineering Department, STFC Daresbury Laboratory, Daresbury, Cheshire WA4 4AD, UK
| | - John Purton
- Computational Science and Engineering Department, STFC Daresbury Laboratory, Daresbury, Cheshire WA4 4AD, UK
| | - William Smith
- Computational Science and Engineering Department, STFC Daresbury Laboratory, Daresbury, Cheshire WA4 4AD, UK
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Hu Y, Wu B, Xu Z, Yang Z, Yang X. Solvation structure and dynamics for passivated Au nanoparticle in supercritical CO2: A molecular dynamic simulation. J Colloid Interface Sci 2011; 353:22-9. [DOI: 10.1016/j.jcis.2010.09.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 09/14/2010] [Accepted: 09/17/2010] [Indexed: 11/26/2022]
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